package yuque.a1至20.CalculateEContinuously;

import java.util.Scanner;

/**
 * ClassName: TriangleArea
 * Package: yuque
 * Description:
 *
 * @Author fjorid
 * @Create 2024/12/30 18:51
 * @Version 1.0
 */
public class TriangleArea {
    public static void main(String[] args) {
        double a,b,c,p,area;
        a=b=c=0.0;
        Scanner scan = new Scanner(System.in);
        a = scan.nextDouble();
        b = scan.nextDouble();
        c = scan.nextDouble();


        p=(a+b+c)/2;

        area=Math.sqrt((p*(p-a)*(p-b)*(p-c)));
        System.out.println(area);
    }


}
